The present invention concerns a grinding machine for pins of heavy crankshafts on which the crankshaft is eccentrically mounted in a rotatable clamping arrangement at both ends, where the crankshaft pin to be ground is located in the rotational center of the clamping arrangement and on which the pin can be ground with a grinding head of a cylindrical grinder, the clamping arrangement being provided with at least one relief arrangement for the crankshaft to supply an eccentrically rotating main bearing with constant, vertically applied force counteracting the dead weight of the crankshaft.
During such grinding operations, the deflection of the crankshaft, eccentrically mounted on both ends, poses a problem when the crankshaft exceeds a certain length and/or weight. The deflection of the crankshaft, caused by its own weight, creates an elastic deformation in the area of the pin to be ground, thus not permitting the grinding operation to maintain the normally required tolerances in roundness and width. To decrease the tolerance deviations due to deflection, the pins to be ground can be supported with a steady. This provides acceptable grinding results in the center range of the crankshaft but exceeds permissible tolerances when grinding pins on both ends of the crankshaft. Due to the unfavorable leverage action, deflection can only be insufficiently prevented by supporting the outer pins in steadies. When grinding outside pins, it has been attempted--in addition to the steady located at the pin to be ground--to provide a rotating disc with eccentric bore and corresponding to the stroke in the center of the crankshaft and to fasten it in such a way that the outside diameter of the disc runs true and is possibly spring-loaded to an extent that it counteracts the deflection of the crankshaft. However, such a support cannot be used on modern and partly automatically operated pin grinding machines, because the disc has to be detached, re-adjusted and possibly completely removed when grinding a neighboring pin.